Spark plug



Jan. 12, 1932. c. E. DEWAR 1,840,437

' SPARK PLUG Original Filed May 13, 1929 Fig.1

Patented Jan. 112, 1932 U i k9;

CHARLES E. DEW'AR, 0F TOLEDO, OHIO, ASSIGNOR TO CHAMPION SPARK PLUG COM- PAINY, OF TOLEDO, OEIO, A CORPORATION OF DELAWARE SPARK PLUG Original application filed May 13, 1929, Serial No. 362,480. Divided and this application filed May 21, 1930. Serial No. 454,278.

This invention relates to spark plugs of the type employed in internal combustion engines, and more particularly to those embodying a so-called X-bend side wire or electrode.

In the use of spark .plugs, it has long been well known that the shape of the electrode forming the spark gap, as well as the spacing thereof, has a most important bearing on the proper functioning of spark plugs in an internal combustion engine, directly afiecting engine performance, particularly as to starting, idling and power output. Furthermore, the shape of the electrodes forming the spark gap as well as the spacing thereof, has direct efiect upon the amount of burning and rate of burning of the electrodes or wires of spark plugs in service in an engine, and consequently determines largely their eflicient life or length of service.-

In the history of spark plug manufacture of the'X-bend type, a vast number of shapes of electrodes have been produced by the vari ous manufacturers. To the best of my knowledge, in all of them'the electrodes have been shaped to form a gap across which the spark would have to jump from a rounded or cylindrical surface to a fiat surface, point or edge from a fiat surface, point or edge to a rounded or cylindrical surface; from point to point; from edge to edge; from a rounded or cylindrical surface to a rounded or cylindrical surface; but never from one fiat sur face to another flat surface parallel therewith. Actual practice has shown very decided advantages in the use of a spark plug of the so-called X-bend side wire or electrode type having a spark gap with-the opposing surfaces of the electrodes flat and the edges sharply defined, as shown in the accompanying drawings. The particular feature of this type of electrode resides in the fact that, due

- to the shape of the bend, oil or moisture does not lodge between the electrodes of the gap, and the spark plug continues to function even in-the presence of an excess of oil in the engine cylinder.

Where the X-bend side wire has been used, one or the other, or both, of the electrodes have been either cut off square on the ends, or

cut oil on an angle, or fashioned to form an edge or edges either rounded or tapered, so that the spark tending to jump regularly between the nearest points of the gap has a very definite tendency to rapidly burn back the electrodes due to the small amount of material at the actual points of the gap next to each other. Where the sparking faces of either or both of the electrodes forming the spark gap are rounded or cylindrical, the gap offers greater resistance to the passage of the spark, affecting both the starting and idling of the motor. The rate of burning of the electrodes from the spark gap is extremely high with any and all types of gap where rounded or cylindrical surfaces, or points or edges, have been used.

It is found in practice that if a spark plug of the so-called X-bend side wire type has the adjacent faces of its electrodes so fashioned that they are flat and parallel to each other with their edges quite sharp, the starting and idling conditions of motors are better, the spark is more intense and the efiicient life of the plug is considerably longer than with plugs of this type heretofore used.

The primary object of the invention is to enhance the practicability and commercial value of spark plugs of the type described in the manner referred to.

The invention is fully described in the following specification and illustrated in the accompanying drawings, in which- Figure 1 is a side elevation of a spark plug embodying the invention with the internal end of the shell broken away;

Fig. 2 is an inner end view thereof;

Fig. 3 is a perspective fragmentary end view of the spark plug with the side electrode removed and showing the fiat face on the center electrode which forms one surface of the sparking gap; and 4 Fig. 4 is anelevation of the inner end portion of a. spark plug the same as shown in Fig. 1 except that it is turned partly around to give a partial View of the terminal end of the side electrode.

This application is a division of my 00-;

pending application Serial No. 362,480, filed May 13, 1929, which illustrates and describes one method of making my improved spark R eferring to the drawings, 1 designates a spark plug adapted for use in connection with a cylinder of an internal combustion engine, 2 the center electrode projecting from the customary insulator 3, and 4 the side electrode projecting from the end 5 of the spark plug shell. The electrode 4 is of the X-bend type and terminates with its free end spaced from the adjacent side of the electrode 2 to form a spark gap 6 therebetween.

The feature of the present invention is to provide the spark gap of a plug of this type with opposing faces which are flat and parallel to each other and have the edges thereof sharp or well defined. This is accomplished in the present instance by providing the center electrode 2 at its outer end portion and at one side thereof with a flat surface 7 which is inclined to the spark plug axis and disposed in a plane substantially at right angles to the direction of projection of the adjacent end portion of the side electrode 1 therefrom.

- The terminal end of the center electrode 2 is also shown as having a bevel 9, but this bevel has nothing to do with the action of the plug after it is produced. In the process employed to produce the opposing parallel surfaces for the spark gap, the end of the electrode is beveled before having its spark gap side flattened to form the surface 7.

The side electrode 4, which is of the X- bend type, has its free end terminating in a flat cross surface, indicated at 8 in Fig. 4,

which is opposed to the flat surface 7 of the center electrode, is parallel thereto and is spaced therefrom a suitable distance to provide a suitable spark jumping gap. In the method described in my said co-pending application, the gap 6 with its fiat parallel opposing surfaces is formed by providing the center electrode with the beveled end portion 9, then mounting the side electrode 4 in the shell in proper position at the side of the center electrode and with its free end substantially in contact with the beveled surface. of the center electrode. A saw or other suitable cutting element is then passed between the adjacent surfaces of the two electrodes so as to produce the spark gap 6 having the opposing fiat parallel surfaces 7 and amount and rate of burning, than has been possible by the use of spark plugs of the X-bend side wire type heretofore employed and of which I have knowledge.

I wish it understood that my invention is not limited to any specific construction, arrangement or form of the parts, as it is capable of numerous modifications and changes Without departing from the spirit of the claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A spark plug having a center electrode projecting straight from the inner end of its core axially thereof, and a side electrode projecting from the inner shell end at an inwardly directed incline to the axis of the centerv electrode, with its end surface flat and spaced from'the side of the center electrode to form a spark gap, the side wall of the gap, which is formed by the center electrode, being flat and parallel to said end surface and being inclined to the center electrode axis.

2. A spark plug having a center electrode and a side electrode, the center electrode projecting straight from the inner end of the plug core axially thereof, and conically reduced at its free end, with one side flattened at an incline to its axis, which incline is substantially the same as the incline of the conical portion, and the side electrode being of the X-bend type and having its free end surface flatv and terminating in s aced parallel relation to the flattened sur ace of the center electrode to cooperate therewith to form a spark gap.

In testimony whereof I have hereunto signed my name to this specification.

CHARLES E. DEWAR.

8 on the respective electrodes, each of which surfaces is of considerable area and provided with a well defined edge portion.

It has been definitely and conclusively proven' by numerous tests and by use under various operating conditions that the provision in a spark plug of the type described of a spark gap having opposed flat parallel surfaces of considerable efiicient sparking area with edges which are sharp or well defined, gives the best starting and idling conditions in a motor, and gives a vastly greater-- life to the spark plug, by the reduction in the" 

